<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
    <div v-if="count > 0">div1</div>
    <div v-else-if="count < 0">div2</div>
    <div v-else>div3</div>
    <hr>
    <input v-model="count">
</div>

<script src="../js/vue.js"></script>
<script>
    //1. 创建Vue核心对象
    new Vue({
        el:"#app",
        data(){
            return {
                count:3
            }
        }
    });
</script>
</body>
</html>